Shear response and mechanism of BFRP bar bolted rock joints under variable shear rates

This study investigates the shear behavior and acoustic emission (AE) characteristics of BFRP bar bolted rock joints under varying shear rates through direct shear tests. Results show that BFRP bar bolted joints exhibit a positive correlation between shear rate and shear strength, stiffness, and dissipated energy, with the latter constituting a higher proportion of total energy than in steel-bolted specimens. The high shear rates enhance BFRP bolt-rock synergy by promoting more complete resin matrix fracture, thereby mobilizing additional fibers to improve stability and strength. BFRP bars demonstrate increased axial force proportion with higher shear rates, whereas steel bars carry a larger share of shear force. The deflection angle and deformation of BFRP bars increase with shear rate, improving their collaborative load-bearing capacity with surrounding rock. The study concludes that BFRP bolts outperform steel bolts under high shear rate conditions (above 12 mm/min) due to their superior energy absorption and load redistribution capabilities. These results highlight the potential value of BFRP bolts in earthquake and explosion engineering applications.